Exploring Cesium and H-Beam Properties Internal to the Lansce H-Ion Source Using Resonant Absorption Spectroscopy and Cavity Ring Down Spectroscopy

Abstract

The Los Alamos Neutron Science Center (LANSCE) H- ion source has provided stable output for decades of LANL mission needs, but its maximum beam output has remained the same at ~15 mA. A roadblock to improving beam output has been a lack of thorough understanding of the internal mechanisms of LANSCE H- ion source. The LANSCE H- Ion Source Laser Diagnostic Stand (HLDS) was recently built and commissioned to explore these internal mechanisms using laser absorption techniques, in particular to measure and diagnose dynamic H- and Cesium (Cs) properties. The Cs density probe is based on resonant absorption of a continuous wave diode laser tuned though the D2 line of cesium (~852 nm). The H- measurement relies on a much weaker photo-ionization process, and therefore relies on a cavity ring down spectroscopy measurement. The design, construction and commissioning of HLDS will be reviewed, the measurements and capabilities using the Cs laser diagnostic will be presented, and the status of the H- laser diagnostic will be discussed.